Like on Mars: life found deep beneath the seabed

US, WASHINGTON (NEWS OBSERVATORY) — Biologists have discovered a real feast of life at a depth of 75 meters under the seabed. Interestingly, this environment is similar in number of parameters to the surface of the Red Planet.

The achievement is described in a scientific article published in the journal Communications Biology.

Samples were collected back in 2010. A research vessel following the Tahiti New Zealand route stopped at three points. At the bottom of the ocean, which has a depth of 5.7 kilometers in these places, a drill sank.

Scientists drilled a well 125 meters deep in the bottom. The first 75 meters were in sedimentary rocks, and then a continuous basaltic rock, once a volcanic lava, began.

Researchers discovered a community of bacteria in extracted stone rods (cores). Unicellular populated narrow (often less than a millimeter wide) basalt cracks filled with clay minerals.

“These cracks -.. A very comfortable place to live in Clay minerals of the earth are like a magic material discovering clay minerals, you will almost always find them in the living microbes,” – says Yohei Suzuki from the University of Tokyo.

However, biologists still did not expect that the rock deep under the seabed would be so densely populated. The microbial population density was 10 billion cells per cubic centimeter of clay rocks.

By this indicator, they turned out to be comparable with the human intestines (!). By the way, in the mud sediments of the seabed at the same points only 100 cells per cubic centimeter were found.

How all these bacteria got there is not very clear. There were no geothermal springs or anything similar at the drilling sites , so microorganisms could not be carried by a stream of water.

Also, biologists found that the samples from three points significantly differed in the strains inhabiting them. Perhaps this is due to the different age of the lava, which has become a haven for microbes: 13.5, 33.5 and 104 million years.

However, bacteria that breathe oxygen and consume ready-made organic substances (rather than synthesizing them from inorganic ones) dominate in all three communities. This is more than surprising for such extreme habitats.

Researchers suggest that clay minerals concentrate nutrients and prevent sea water from dissolving them. This explains such a celebration of life in the depths of basalt rock.

It is curious that the conditions in these cracks are pretty much reminiscent of Martian ones.

“A neutral or slightly alkaline pH, low temperature, moderate salinity, an iron-rich environment, basalt rocks – all these conditions make the deep ocean closer to the surface of Mars,” said Suzuki.

In this regard, the scientist and his colleagues have already begun cooperation with NASA. They are going to develop methods for analyzing Martian soil that would help to detect such bacteria-rich cracks on the Red Planet.

Note that for samples from the bottom of the ocean, with all the available arsenal of terrestrial laboratories, it was not at all simple. But the researcher is optimistic about the new task.

“Now I almost expect to be able to find life on Mars,” Suzuki fantasizes.